Moral Foundations Theory was created to understand why morality varies so much across cultures yet still shows so many similarities and recurrent themes.
In brief, the theory proposes that five innate and universally available psychological systems are the foundations of "intuitive ethics." Each culture then constructs virtues, narratives, and institutions on top of these foundations, thereby creating the unique moralities we see around the world, and conflicting within nations too. The foundations are:
1) Harm/care, related to our long evolution as mammals with attachment systems and an ability to feel (and dislike) the pain of others. This foundation underlies virtues of kindness, gentleness, and nurturance.
2) Fairness/reciprocity, related to the evolutionary process of reciprocal altruism. This foundation generates ideas of justice, rights, and autonomy.
3) Ingroup/loyalty, related to our long history as tribal creatures able to form shifting coalitions. This foundation underlies virtues of patriotism and self-sacrifice for the group. It is active anytime people feel that it's "one for all, and all for one."
4) Authority/respect, shaped by our long primate history of hierarchical social interactions. This foundaiton underlies virtues of leadership and followership, including deference to legitimate authority and respect for traditions.
5) Purity/sanctity, shaped by the psychology of disgust and contamination. This foundation underlies religious notions of striving to live in an elevated, less carnal, more noble way. It underlies the widespread idea that the body is a temple which can be desecrated by immoral activities and contaminants (an idea not unique to religious traditions).
Much of our present research involves applying the theory to political "cultures" such as those of liberals and conservatives. The current American culture war, we have found, can be seen as arising from the fact that liberals try to create a morality relying almost exclusively on the Harm/Care and Fairness/Reciprocity foundations; conservatives, especially religious conservatives, use all five foundations, including Ingroup/Loyalty, Authority/Respect, and Purity/Sanctity. You can find out your own moral foundations profile at www.YourMorals.org